Simplify the following expression: $a = \dfrac{3}{4p} - \dfrac{7}{6p}$
Explanation: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $4p$ and $6p$ $\lcm(4p, 6p) = 12p$ $ a = \dfrac{3}{3} \cdot \dfrac{3}{4p} - \dfrac{2}{2} \cdot \dfrac{7}{6p} $ $a = \dfrac{9}{12p} - \dfrac{14}{12p}$ $a = \dfrac{9 -14}{12p}$ $a = \dfrac{-5}{12p}$